Breastfeeding challenges

My daughter is now 18 days old, but spent the first 17 days in
hospital. She was on a ventilator for 8 days, began tube feeding EBM at
day 5, mouth feeding 2x/day at day 11 - via bottle which she didn't
take to well at all. At 14 days started on the breast. She immediately
took to it on her first try, but subsequent feedings didn't work. On
day 15 I fed on demand as much as possible, and she'd take the breast
about 30% of the time, the other times we'd (myself, the nurses, the
LC) give her EBM via syringe or bottle, tho she was still lousy on the
bottle. The NG tube was removed (well, she pulled it out and the nurse
agreed to leave it out). Day 16 she suddenly liked the bottle more and
did well at the breast about 50% of the time.

While at first we all said NO bottles, even the LC agreed we needed to
get her fed so we could get her home (she was healthy by now and
feeding was the only hold up), and to do whatever it took. So now we're
home.

She seems to latch on well most of the time, I can hear her swallow.
Tho there are times I think she's just got the nipple - I use my hand
to stimulate milk flow and I know she's getting it. She'll feed 15 mins
on one side, konk out totally for 15 mins or so, then is hungry again
but will only spend maybe 5 mins on the other side at most. She will
feed every 1.5 hrs, max 2hrs. She did well all day, but at night she
doesn't wake and I have to wake her at 3hrs to feed. She doesn't wake
up fully and really struggles with the breast. In the day she'll use
her mouth to seek it, but at night she purses her lips and wants
nothing to do with it. So I caved and gave her EBM, and this morning
she's doing ok with the breast directly again.

Any suggestions to improve the night time feeding? I haven't mastered
the knack of laying on my side to feed, but will practice that. She
had oral aversion issues initially due to the ventilator, so we were
less worried about nipple confusion and more about her just taking
something.